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Bibiseptium
Bibiseptium, Bbs, is the temporary name for element 227. NUCLEAR What follows is based on a first-order, liquid-drop assessment of where the outer boundary of the nuclear world is. Assume cautious values for how many neutrons a nucleus with 227 protons can bind (high neutron dripline) and how few it can have before it fissions immediately regardless of how much the structure it can develop stabilizes it (low must-fission curve). Assume, too, that anything that lasts long enough so that protons and neutrons can be treated as particles rather than collections of quarks (is causal) might be a nucleus. Under these conditions, Bbs isotopes are theoretically possible between Bbs 725 and Bbs 1021 (see "The Final Element", this wiki). Bbs 725 through Bbs 802 are expected to decay by beta emission if they don’t fission quickly. Above that value of A, the confident neutron dripline, drops may decay by neutron emission before they can fission. (Structural correction does not affect neutron emission.) Bbs 802 needs at least 1.2 times the structural correction energy required to prevent fission in worst-case nuclei in the A = 480 region(1), and Bbs 759 and smaller require at least 2.0 times as much. Predicting whether or not the structure a nuclear drop can develop will allow the drop to survive for the 10^-14 sec required for it to bind an electron and so become an atomic nucleus is not usually possible at this time. Neutron shell closures have been predicted at N = 772, 644, and 524(2), The first two are expected to allow some nuclei in the vicinities of Bbs 999 and Bbs 871 – if neutron emission does not occur. The former requires only a little shell correction to survive, but is likely to decay by neutron emission. The second requires moderate correction (5 MeV), and is comparatively likely to be immune to neutron decay (9% above the confident dripline). The third is not expected to be able to stabilize nuclei. Even with these possibilities, no isotopes of Bbs are likely and the band from Bbs 725 to Bbs 740 can be ignored. ATOMIC Conventional techniques for computing an element's electron structure cannot be used to study Bbs. Its nuclear size is so large that the concept of time-invariant orbitals no longer applies. In addition, it is so large that its nuclear shape probably causes different isotopes of Bbs to have different electronic structures. (It is no longer an element in the chemical sense.) FORMATION If it can exist at all, ions of this element may form when material from roughly 1 km depth is ejected from a disintegrating neutron star during a merger. It may be impossible for lighter isotopes to form in this way. REFERENCES 1. "Decay Modes and a Limit of Existence of Nuclei"; H. Koura; 4th Int. Conf. on the Chemistry and Physics of Transactinide Elements; Sept. 2011. 2. "Magic Numbers of Ultraheavy Nuclei"; V. Yu Denisov; Physics of Atomic Nuclei, v. 68, no. 7, pp 1133-1137; 2005. (12-01-19)